Neurokinin-1 (NK-1) receptor and brain-derived neurotrophic factor (BDNF) gene expression is differentially modulated in the rat spinal dorsal horn and hippocampus during inflammatory pain
© Duric and McCarson; licensee BioMed Central Ltd. 2007
Received: 22 August 2007
Accepted: 31 October 2007
Published: 31 October 2007
Persistent pain produces complex alterations in sensory pathways of the central nervous system (CNS) through activation of various nociceptive mechanisms. However, the effects of pain on higher brain centers, particularly the influence of the stressful component of pain on the limbic system, are poorly understood. Neurokinin-1 (NK-1) receptors and brain-derived neurotrophic factor (BDNF), known neuromediators of hyperalgesia and spinal central sensitization, have also been implicated in the plasticity and neurodegeneration occurring in the hippocampal formation during exposures to various stressors. Results of this study showed that injections of complete Freund's adjuvant (CFA) into the hind paw increased NK-1 receptor and BDNF mRNA levels in the ipsilateral dorsal horn, supporting an important role for these nociceptive mediators in the amplification of ascending pain signaling. An opposite effect was observed in the hippocampus, where CFA down-regulated NK-1 receptor and BDNF gene expression, phenomena previously observed in immobilization models of stress and depression. Western blot analyses demonstrated that in the spinal cord, CFA also increased levels of phosphorylated cAMP response element-binding protein (CREB), while in the hippocampus the activation of this transcription factor was significantly reduced, further suggesting that tissue specific transcription of either NK-1 or BDNF genes may be partially regulated by common intracellular transduction mechanisms mediated through activation of CREB. These findings suggest that persistent nociception induces differential regional regulation of NK-1 receptor and BDNF gene expression and CREB activation in the CNS, potentially reflecting varied roles of these neuromodulators in the spinal cord during persistent sensory activation vs. modulation of the higher brain structures such as the hippocampus.
To date, pain-induced peripheral and central sensory activation has been well characterized; however, little emphasis has been placed on studying the physiological mechanisms of the stress-like component of pain and its relationship to mood or affect. The importance of the emotional aspects of chronic pain and their impact on cognition and the overall perception of the nociceptive stimuli is augmented by clinical observations that majority of chronic pain patients often suffer from various forms of depressive illnesses [1–4]. The hippocampus, one of the main regulators of affect within the limbic system, has been previously shown to exhibit a robust stress-induced neurodegenerative plasticity related to the pathophysiology of depression [5–8]. Furthermore, the hippocampus has also been associated with the processing of pain-related information, particularly its potential role in shaping the affective-motivational response to noxious sensory stimulation. For example, peripheral administration of formalin was shown to attenuate levels of Fos protein in the rat hippocampus , while microinjections of lidocaine or glutamate receptor antagonists directly into the dorsal hippocampal formation decreased formalin-related nociceptive behaviors [10, 11].
The tachykinin neuropeptide substance P (SP) and brain-derived neurotrophic factor (BDNF), each expressed by a subset of primary sensory neurons, are known modulators of nociceptive processing within the CNS [12–14]. Upon tissue injury or noxious stimulation, SP and BDNF are released into laminae I and II of the spinal cord dorsal horn, where through activation of their respective postsynaptic receptors, neurokinin-1 (NK-1) and tyrosine kinase B (trkB), contribute to development of hyperalgesia and central sensitization associated with chronic pain [15–18]. Both NK-1 receptors and BDNF are also highly expressed in the limbic system, primarily the amygdala, the hippocampus and the hypothalamus [14, 19, 20]. Their potential involvement in the processing of mood/affect has been suggested by clinical observations that NK-1 receptor antagonists have antidepressant properties [21, 22], while amplification of hippocampal BDNF levels is considered to be a possible common down-stream effect of various antidepressant psychopharmacotherapies [23, 24]. However, the influences of these neuromediators on modulation of neuronal plasticity following chronic pain, particularly their functional differences in the spinal dorsal horn vs. the hippocampus, are still largely undefined.
Previous studies have shown that intracellular transcriptional regulation of NK-1 receptor and BDNF genes, during either spinal nociceptive processing or stress-related stimulation of hippocampus, may be modulated by transduction pathways involving activation of extracellular signal-regulated kinases (ERK)/cAMP response element binding protein (CREB) cascades [25–29]. Once activated by wide variety of extracellular signals through dual phosphorylation at threonine (Thr202) and tyrosine (Tyr204) sites , p-ERK proteins translocate from the cytoplasm into the nucleus and activate transcription factors such as CREB. Subsequently, CREB phosphorylated at serine133 (p-CREB) further induces transcription of genes containing cAMP response element (CRE) binding sites in their promoter regions , such as c-fos, NK-1, BDNF, and trkB [32–34]. The ERK/CREB-dependent cascade represents one of many intracellular pathways through which the extracellular stimuli, such as pain, may be transduced into post-translational and transcriptional responses within the neuronal tissue .
To address nociceptive regulation of regions of the CNS related to potentially distinct sensory vs. affective functions, we measured NK-1 receptor and BDNF gene expression in the spinal cord and the hippocampus following administration of complete Freund's adjuvant (CFA) into the rat hind paw. Furthermore, Western blot analysis was used to assess whether the changes in transcription of these two genes was correlated with CFA-evoked alterations in amounts of nuclear p-ERK and p-CREB proteins.
Animal housing and handling
Young adult male Sprague Dawley rats (Harlan Farms, Indianapolis, IN), used for all experiments, were age matched (7–8 weeks old) at the beginning of the treatments. All animals were allowed at least one week of habituation before any treatments were applied. The maintenance of the rat colony and all the animal treatments were in accordance with NIH laboratory care standards and approved by the University of Kansas Medical Center Institutional Animal Care and Use Committee. Efforts were made to minimize animal suffering and to reduce the number of animals used in this study. Rats were housed (12 h light/dark cycle) in groups of three per cage with ad libitum access to food and water; they were mixed together so there is one member of each treatment group in every cage. All rats, including the sham control group, were handled the same way to reduce the effects of stress associated with handling on the results.
Rats (200–300 g) received a subcutaneous (s.c.) injection of 50 μL of Complete Freund's Adjuvant (CFA) (Sigma Chemical Co., St. Louis, MO) into the plantar aspect of the right hind paw. To establish a time-course of CFA's effects, rats were decapitated at several time points after CFA injection: 24 h (n = 5 or 6), 4 days (n = 6) and 10 days (n = 6). In order to address the long-term effects of peripheral nociception, two additional groups of animals received either a single (1×; CFA injection on day 0; n = 6) or triple (3×; CFA injections on days 0, 7 and 14; n = 5 or 6) CFA administrations over a period of 21 days. Sham control (n = 5 or 6) animals received no injection of CFA into the hind paw, but were momentarily restrained and their right hind paw manipulated. Otherwise, controls were handled identically to the treatment animals in terms of housing regime, daily transport from the animal facilities to the laboratory, and interactions with the handler.
Immediately after decapitation, rat brains and spinal cords from the same animals were removed. Brains were dissected along the sagittal midline, followed by bilateral removal of the hippocampus. Spinal cord tissues were rapidly removed using hydraulic pressure (a forceful injection of ice-cold isotonic saline) applied to the caudal end of the vertebral canal with a 60 ml syringe and a 16-gauge needle. The lumbar portions (L1–L6) of the vertebral column were then dissected. The dorsal horn regions were dissected by cutting the lumbar portion of the spinal cord along the sagittal axis and dividing it into quarters. Only the ipsilateral side of the spinal cord was assayed.
Solution hybridization – nuclease protection assays
The NK-1 receptor and BDNF (BDNF cDNA plasmid was graciously provided by Ronald Duman, Ph.D., Yale Medical Center) sense and antisense cRNA probes were generated by an in vitro run-off transcription reaction [23, 35]. Synthesis of the antisense 32P-labeled cRNA probes using [α-32P]UTP (3000 Ci/mmol) was based on the protocol suggested by Promega (Madison, WI). Probes were purified through a NucAway spin column (Ambion, Austin, TX), and DNA template was subsequently digested using RQ1 Dnase (Promega, Madison, WI). The total cellular RNAs were extracted from both the hippocampal and spinal tissue samples using a rapid quanidinium isothiocyanate-phenol/chloroform extraction method and then assayed for NK1, BDNF or β-actin mRNAs using solution hybridization – nuclease protection assays as previously described [35–37]. Specific mRNA amounts were determined by comparison to cRNA quantitation standards. Levels of β-actin mRNA, unaffected by peripheral inflammatory nociception in either spinal cord or the hippocampus, served as gel loading controls and to ensure that the detected changes in NK-1 receptor and BDNF mRNA levels were not due to a CFA-related global modulation of gene expression within the CNS. Data values for NK-1 receptor and BDNF gene expression are reported as pg specific mRNA/ng β-actin mRNA [mean ± S.E.M.].
Western blot analysis
Fresh ipsilateral dorsal horns of the spinal cord and bilateral hippocampal tissues were initially homogenized in lysis buffer containing a cocktail of phosphatase and proteinase inhibitors, followed by the isolation of the nuclear fractions using the Nuclear extract kit from Active Motif (Carlsbad, CA). Tissue protein concentrations were determined using the BCA protein assay kit (Pierce, Rockford, IL). Protein samples were electrophoretically separated on an SDS-PAGE gel (10% Tris-HCl; Bio-Rad, Hercules, CA) and transferred to polyvinylidene difluoride membranes (0.2 μm pores; Millipore, Bedford, MA). The membranes were blocked with 2% bovine serum albumin (BSA) for 2 h at room temperature (RT) and then incubated with overnight at 4°C with anti-p-ERK (detects ERK1/2 MAPKs phosphorylated at Tyr204; 1:200; Santa Cruz Biotechnology) or anti-p-CREB (detects CREB phosphorylated at Ser133; 1:1000; Upstate Cell Signaling Solutions) primary antibodies. All antibodies were diluted in Tris-buffered saline solution containing 0.5% Tween 20 (TBST) and 0.2% BSA. After washing in TBST, the blots were incubated with horseradish peroxidase (HRP)-conjugated secondary antibody for 2 h at RT (1:2000, Santa Cruz Biotechnology for p-ERK1/2; and 1:70000, Jackson Laboratories for p-CREB). Following the rinse in TBST, the blots were developed using enhanced chemilluminescence for 1 min and exposed onto Kodak MR autoradiographic film. To obtain loading controls, the blots were incubated in stripping buffer (1 M glycine pH 7.0, 20% SDS) for 1 h at 60°C and reprobed with antibodies recognizing total protein (1:1000, Cell Signaling Technology primary antibody for ERK1/2 or CREB; secondary antibody: 1:10000, Santa Cruz Biotechnology). Autoradiographs were scanned using a Gel-Doc imaging system (Bio-Rad, Milan, Italy) and analyzed with Quantity One 1-D software (Bio-Rad, Hercules, CA).
Data from all the experiments were analyzed using analysis of variance (ANOVA) with either Fisher's PLSD or Student-Newman-Keuls' tests used for post-hoc comparisons. Significance was considered to be p ≤ 0.05.
Nociception-evoked regulation of NK-1 receptor and BDNF gene expression in the spinal cord and hippocampus
Nociception-evoked activation of ERK and CREB proteins in the spinal cord and hippocampus
The mechanisms by which inflammatory nociception is processed within the spinothalamic pathways of the CNS have been well established at both cellular and molecular levels. However, the impact of painful stimulation on the higher brain centers, mainly the emotion- and cognition-processing components of the CNS, is still unclear. Besides the sensory aspects of nociception, a negative impact on affect is essential for accurate characterization of a stimulus as "painful". Therefore, improved understanding of how pain affects the mood-controlling regions of the brain would be very beneficial to treatment of chronic pain in the clinical setting.
The experiments in this study were designed to conduct a direct comparison of CFA-induced peripheral nociception on the expression of NK-1 receptor and BDNF in the spinal cord and hippocampal formation, one of the central limbic regions involved in the regulation of affect. Current results demonstrate that NK-1 receptor and BDNF mRNA levels are initially increased in the ipsilateral dorsal horn at 24 h and 4 days post CFA (Fig. 1), consistent with results of other studies [35, 39, 40]. Previous reports have suggested that SP and BDNF may co-localize in the same large dense-core vesicles (LDCVs) of the small diameter primary nociceptors, and that their release is dependent on the activation of tyrosine kinase A (trkA) receptors due to enlarged levels of nerve growth factor (NGF) in the periphery . Increases in NK-1 receptor and BDNF gene expression in the dorsal horn likely represent a secondary effect resulting from facilitated activation of NMDA, NK-1 and trkB receptors located on the secondary afferents. This effect is considered to be directly related to increased SP and BDNF release from the terminals of primary nociceptors in response to peripheral inflammation .
Another important aspect of this study was to address the long-term effects of nociception on CNS gene plasticity. Thus, 10 and 21 day time points were included in the experimental design. Previously we reported that a single injection of CFA produces thermal and mechanical hyperalgesia for about 10–12 days post injection; however, when CFA was administered three times (weekly injections) over 21 day period, hyperalgesia was present throughout the entire time course . Therefore, we also compared the effects of single vs. triple CFA treatments on gene expression over a 21 day period. Spinal NK-1 receptor gene expression was not affected at these later time points (Fig. 1A), while the BDNF mRNA levels continued to increase, with the most robust response occurring after three weekly administrations of CFA (Fig. 1B). The discrepancy in pain-induced regulation of these two genes at later time points could be due to an array of factors, ranging from differences in susceptibility during long-term sensory regulation to diverse intracellular conditions required for induction of transcription or stabilization of the mRNAs. Besides having roles in activity-dependent excitability, BDNF is also important for neuronal survival, regeneration, outgrowth and overall maintenance , suggesting that continuous expression of the BDNF gene may be more important in development of latent stages of chronic pain. Overall, the initial nociception-induced up-regulation of NK-1 receptor and BDNF gene expression in the spinal cord supports the requirement of these neuromodulators for the maximum amplification of ascending pain signaling during central sensitization.
Nociceptive information from the periphery and the spinal cord is transmitted to the brain mainly through spinothalamic and parabrachial ascending pathways . Furthermore, complex neuronal networks connect the parabrachial area or the thalamus to the limbic regions such as the hippocampus, the amygdala and the hypothalamus, which can modulate spinal nociceptive processing through activation of descending monoaminergic pathways from the brain stem . However, the limbic areas of the brain, particularly the hippocampus, are also involved in control of stress responses and are considered to be the main regulators of mood or affect. CFA evoked robust decreases in NK-1 receptor and BDNF mRNA levels in the hippocampal formation, contrary to the prominent up-regulation seen in the spinal cord. A similar type of hippocampal plasticity was previously observed after either peripheral formalin injections or immobilization stress, as both of these stimuli were shown to down-regulate hippocampal NK-1 and BDNF gene expression [36, 38, 41]. The mechanisms responsible for the similarity between nociception- and stress-evoked effects in the hippocampus are not fully understood, but previous results suggest that maintenance of the nociceptive regulation of the hippocampus is not dependent upon continuous activation of the HPA axis . The current results provide additional evidence that persistent nociception may have a significant effect on modulation of the higher brain centers, further suggesting that both the NK-1 receptor and BDNF may play a prominent role in pain processing within limbic structures such as the hippocampus.
Previous studies have suggested that CNS events leading to central sensitization during peripheral inflammation, hippocampal regulation due to stress, or long-term potentiation associated with spatial learning and memory may be dependent on similar intracellular transduction mechanisms, primarily the activation of cytosolic ERK and subsequent phosphorylation of nuclear CREB [29, 45–50]. Both of these proteins are important for activity-dependent gene expression, and are thought to play a key role in synaptic plasticity contributing to translation of acute stimuli into long-term events such as the development and maintenance of chronic pain or depression. Western blot analysis showed that 24 h or 21 days after CFA administration, p-ERK levels were generally not altered in either the dorsal horn or the hippocampus, except for slight increases in spinal p-ERK2 (Fig. 4). Previous reports suggest that robust activation of spinal ERK following CFA [25, 26, 50] may be transient, since p-ERK levels usually peak within minutes after application of painful stimulus and then start to diminish due to increased dephosphorylation by various MAP kinase phosphatases [25, 26, 50]. We addressed initial p-ERK activation by assessing protein levels at 10 min after 50 μL of CFA (data not shown); however, changes in the regulation of either spinal or hippocampal p-ERK levels were not observed at this time point either. The discrepancy with previous reports may be due to a lesser amount of CFA used in our experiments, methods and/or quantitiative end-points used in each study, or differences in specific time points when protein changes were measured. However, eventual activation of transduction proteins such as ERKs and other intracellular kinases often initiates long-term synaptic plasticity through modulation of post-translational and transcriptional events that outlast both the initiating stimulus and kinase activation . This may, in part, explain increased levels of nuclear p-CREB in the ipsilateral dorsal horn at both 24 h and 21 days (3×) after CFA treatments (Fig. 5). Elevated activation of CREB in the spinal cord further supports the role of this transcription factor in persistent nociception. Similar to NK-1 receptor and BDNF gene expression, CFA diminished hippocampal p-CREB levels, a phenomenon reminiscent of that previously reported during stress and depression [24, 51], possibly by triggering intracellular events common to both types of stimuli. Besides ERKs, the activation of CREB may be coupled to other transduction factors, primarily the calcium/calmodulin-dependent protein kinase (CaM kinases)- or protein kinase A (PKA)-dependent cascades [27, 52], to trigger the transcription of target genes such as NK-1 receptor and BDNF. Due to their similar patterns of nociception-evoked regulation, these data imply that expression of NK-1 receptor and BDNF genes could be at least partially controlled by CREB-dependent intracellular signaling in both the sensory and affective systems of the CNS . However, the transcription of NK-1 receptor gene at the later phase of inflammation is probably dependent on other regulatory pathways, since no changes were observed in the dorsal horn 21 days after CFA.
Our original hypothesis was that NK-1 receptor and BDNF gene expression may be co-regulated by peripheral nociception, but the results of this study demonstrated that is not the case, particularly at the longest time points tested in our chronic pain model. However, diverse patterns of gene expression suggest that NK-1 receptors and BDNF may have different roles in various regions of the CNS during chronic pain, since the spinal cord is an integral component of the sensory system, while the hippocampus is a part of the limbic system and a key contributor in regulation of affect. Novel information about the modulation of sensitivity, function, and plasticity of the genes encoding relevant neurotransmitters and their receptors, which contribute to the overall perception of pain, may give us a better idea of how to control the negative effects of pain on the mood and may provide a major insight into the development of improved therapeutic regimens for treating depression-like aspects of chronic pain.
analysis of variance
brain-derived neurotrophic factor
- CaM kinase:
calcium/calmodulin-dependent protein kinase
cyclic adenosine 3', 5' – monophosphate
complete Freund's adjuvant
central nervous system
cAMP response element
cAMP response element binding protein
extracellular signal-regulated kinase
mitogen-activated protein kinase
protein kinase A
tyrosine kinase B
The authors would like to thank Michelle Winter for her expert technical and editorial assistance. This project was supported in part by DA12505 (KMcC).
- Ruoff GE: Depression in the patient with chronic pain. J Fam Pract 1996,43(6 Suppl):S25–33; discussion S34.PubMedGoogle Scholar
- Bair MJ, Robinson RL, Katon W, Kroenke K: Depression and pain comorbidity: a literature review. Arch Intern Med 2003,163(20):2433–2445. 10.1001/archinte.163.20.2433PubMedView ArticleGoogle Scholar
- Gallagher RM, Verma S: Managing pain and comorbid depression: A public health challenge. Semin Clin Neuropsychiatry 1999,4(3):203–220.PubMedGoogle Scholar
- Mossey JM, Gallagher RM: The longitudinal occurrence and impact of comorbid chronic pain and chronic depression over two years in continuing care retirement community residents. Pain Med 2004,5(4):335–348. 10.1111/j.1526-4637.2004.04041.xPubMedView ArticleGoogle Scholar
- Woolley CS, Gould E, McEwen BS: Exposure to excess glucocorticoids alters dendritic morphology of adult hippocampal pyramidal neurons. Brain Res 1990,531(1–2):225–231. 10.1016/0006-8993(90)90778-APubMedView ArticleGoogle Scholar
- Watanabe Y, Gould E, McEwen BS: Stress induces atrophy of apical dendrites of hippocampal CA3 pyramidal neurons. Brain Res 1992,588(2):341–345. 10.1016/0006-8993(92)91597-8PubMedView ArticleGoogle Scholar
- Gould E, Tanapat P: Stress and hippocampal neurogenesis. Biol Psychiatry 1999,46(11):1472–1479. 10.1016/S0006-3223(99)00247-4PubMedView ArticleGoogle Scholar
- McEwen BS: Stress and hippocampal plasticity. Annu Rev Neurosci 1999, 22: 105–122. 10.1146/annurev.neuro.22.1.105PubMedView ArticleGoogle Scholar
- Khanna S, Chang LS, Jiang F, Koh HC: Nociception-driven decreased induction of Fos protein in ventral hippocampus field CA1 of the rat. Brain Res 2004,1004(1–2):167–176. 10.1016/j.brainres.2004.01.026PubMedView ArticleGoogle Scholar
- McKenna JE, Melzack R: Analgesia produced by lidocaine microinjection into the dentate gyrus. Pain 1992,49(1):105–112. 10.1016/0304-3959(92)90195-HPubMedView ArticleGoogle Scholar
- McKenna JE, Melzack R: Blocking NMDA receptors in the hippocampal dentate gyrus with AP5 produces analgesia in the formalin pain test. Exp Neurol 2001,172(1):92–99. 10.1006/exnr.2001.7777PubMedView ArticleGoogle Scholar
- Vaught JL: Substance P antagonists and analgesia: a review of the hypothesis. Life Sci 1988,43(18):1419–1431. 10.1016/0024-3205(88)90253-6PubMedView ArticleGoogle Scholar
- Henry JL: Substance P and inflammatory pain: potential of substance P antagonists as analgesics. Agents Actions Suppl 1993, 41: 75–87.PubMedGoogle Scholar
- Malcangio M, Lessmann V: A common thread for pain and memory synapses? Brain-derived neurotrophic factor and trkB receptors. Trends Pharmacol Sci 2003,24(3):116–121. 10.1016/S0165-6147(03)00025-7PubMedView ArticleGoogle Scholar
- Woolf CJ, Salter MW: Neuronal plasticity: increasing the gain in pain. Science 2000,288(5472):1765–1769. 10.1126/science.288.5472.1765PubMedView ArticleGoogle Scholar
- Heppenstall PA, Lewin GR: BDNF but not NT-4 is required for normal flexion reflex plasticity and function. Proc Natl Acad Sci U S A 2001,98(14):8107–8112. 10.1073/pnas.141015098PubMed CentralPubMedView ArticleGoogle Scholar
- Kerr BJ, Bradbury EJ, Bennett DL, Trivedi PM, Dassan P, French J, Shelton DB, McMahon SB, Thompson SW: Brain-derived neurotrophic factor modulates nociceptive sensory inputs and NMDA-evoked responses in the rat spinal cord. J Neurosci 1999,19(12):5138–5148.PubMedGoogle Scholar
- Hunt SP, Mantyh PW: The molecular dynamics of pain control. Nat Rev Neurosci 2001,2(2):83–91. 10.1038/35053509PubMedView ArticleGoogle Scholar
- Maeno H, Kiyama H, Tohyama M: Distribution of the substance P receptor (NK-1 receptor) in the central nervous system. Brain Res Mol Brain Res 1993,18(1–2):43–58. 10.1016/0169-328X(93)90172-LPubMedView ArticleGoogle Scholar
- De Felipe C, Herrero JF, O'Brien JA, Palmer JA, Doyle CA, Smith AJ, Laird JM, Belmonte C, Cervero F, Hunt SP: Altered nociception, analgesia and aggression in mice lacking the receptor for substance P. Nature 1998,392(6674):394–397. 10.1038/32904PubMedView ArticleGoogle Scholar
- Kramer MS, Cutler N, Feighner J, Shrivastava R, Carman J, Sramek JJ, Reines SA, Liu G, Snavely D, Wyatt-Knowles E, Hale JJ, Mills SG, MacCoss M, Swain CJ, Harrison T, Hill RG, Hefti F, Scolnick EM, Cascieri MA, Chicchi GG, Sadowski S, Williams AR, Hewson L, Smith D, Carlson EJ, Hargreaves RJ, Rupniak NM: Distinct mechanism for antidepressant activity by blockade of central substance P receptors. Science 1998,281(5383):1640–1645. 10.1126/science.281.5383.1640PubMedView ArticleGoogle Scholar
- Rupniak NM, Kramer MS: Discovery of the antidepressant and anti-emetic efficacy of substance P receptor (NK1) antagonists. Trends Pharmacol Sci 1999,20(12):485–490. 10.1016/S0165-6147(99)01396-6PubMedView ArticleGoogle Scholar
- Nibuya M, Morinobu S, Duman RS: Regulation of BDNF and trkB mRNA in rat brain by chronic electroconvulsive seizure and antidepressant drug treatments. J Neurosci 1995,15(11):7539–7547.PubMedGoogle Scholar
- Duman RS, Heninger GR, Nestler EJ: A molecular and cellular theory of depression. Arch Gen Psychiatry 1997,54(7):597–606.PubMedView ArticleGoogle Scholar
- Ji RR, Baba H, Brenner GJ, Woolf CJ: Nociceptive-specific activation of ERK in spinal neurons contributes to pain hypersensitivity. Nat Neurosci 1999,2(12):1114–1119. 10.1038/16040PubMedView ArticleGoogle Scholar
- Ji RR, Befort K, Brenner GJ, Woolf CJ: ERK MAP kinase activation in superficial spinal cord neurons induces prodynorphin and NK-1 upregulation and contributes to persistent inflammatory pain hypersensitivity. J Neurosci 2002,22(2):478–485.PubMedGoogle Scholar
- Kawasaki Y, Kohno T, Zhuang ZY, Brenner GJ, Wang H, Van Der Meer C, Befort K, Woolf CJ, Ji RR: Ionotropic and metabotropic receptors, protein kinase A, protein kinase C, and Src contribute to C-fiber-induced ERK activation and cAMP response element-binding protein phosphorylation in dorsal horn neurons, leading to central sensitization. J Neurosci 2004,24(38):8310–8321. 10.1523/JNEUROSCI.2396-04.2004PubMedView ArticleGoogle Scholar
- Kodama M, Russell DS, Duman RS: Electroconvulsive seizures increase the expression of MAP kinase phosphatases in limbic regions of rat brain. Neuropsychopharmacology 2005,30(2):360–371. 10.1038/sj.npp.1300588PubMedView ArticleGoogle Scholar
- Ying SW, Futter M, Rosenblum K, Webber MJ, Hunt SP, Bliss TV, Bramham CR: Brain-derived neurotrophic factor induces long-term potentiation in intact adult hippocampus: requirement for ERK activation coupled to CREB and upregulation of Arc synthesis. J Neurosci 2002,22(5):1532–1540.PubMedGoogle Scholar
- Chang L, Karin M: Mammalian MAP kinase signalling cascades. Nature 2001,410(6824):37–40. 10.1038/35065000PubMedView ArticleGoogle Scholar
- Impey S, Obrietan K, Storm DR: Making new connections: role of ERK/MAP kinase signaling in neuronal plasticity. Neuron 1999,23(1):11–14. 10.1016/S0896-6273(00)80747-3PubMedView ArticleGoogle Scholar
- Lonze BE, Ginty DD: Function and regulation of CREB family transcription factors in the nervous system. Neuron 2002,35(4):605–623. 10.1016/S0896-6273(02)00828-0PubMedView ArticleGoogle Scholar
- Nibuya M, Nestler EJ, Duman RS: Chronic antidepressant administration increases the expression of cAMP response element binding protein (CREB) in rat hippocampus. J Neurosci 1996,16(7):2365–2372.PubMedGoogle Scholar
- Hershey AD, Dykema PE, Krause JE: Organization, structure, and expression of the gene encoding the rat substance P receptor. J Biol Chem 1991,266(7):4366–4374.PubMedGoogle Scholar
- McCarson KE, Krause JE: NK-1 and NK-3 type tachykinin receptor mRNA expression in the rat spinal cord dorsal horn is increased during adjuvant or formalin-induced nociception. J Neurosci 1994,14(2):712–720.PubMedGoogle Scholar
- Duric V, McCarson KE: Hippocampal neurokinin-1 receptor and brain-derived neurotrophic factor gene expression is decreased in rat models of pain and stress. Neuroscience 2005,133(4):999–1006. 10.1016/j.neuroscience.2005.04.002PubMedView ArticleGoogle Scholar
- Allen AL, Cortright DN, McCarson KE: Formalin- or adjuvant-induced peripheral inflammation increases neurokinin-1 receptor gene expression in the mouse. Brain Res 2003,961(1):147–152. 10.1016/S0006-8993(02)03948-3PubMedView ArticleGoogle Scholar
- Duric V, McCarson KE: Effects of analgesic or antidepressant drugs on pain- or stress-evoked hippocampal and spinal neurokinin-1 (NK-1) receptor and brain-derived neurotrophic factor (BDNF) gene expression in the rat. J Pharmacol Exp Ther 2006.Google Scholar
- Cho HJ, Kim SY, Park MJ, Kim DS, Kim JK, Chu MY: Expression of mRNA for brain-derived neurotrophic factor in the dorsal root ganglion following peripheral inflammation. Brain Res 1997,749(2):358–362. 10.1016/S0006-8993(97)00048-6PubMedView ArticleGoogle Scholar
- Lee SL, Kim JK, Kim DS, Cho HJ: Expression of mRNAs encoding full-length and truncated TrkB receptors in rat dorsal root ganglia and spinal cord following peripheral inflammation. Neuroreport 1999,10(13):2847–2851. 10.1097/00001756-199909090-00027PubMedView ArticleGoogle Scholar
- Duric V, McCarson KE: Persistent Pain Produces Stress-like Alterations in Hippocampal Neurogenesis and Gene Expression. J Pain 2006,7(8):544–555. 10.1016/j.jpain.2006.01.458PubMedView ArticleGoogle Scholar
- Duman RS, Malberg J, Nakagawa S, D'Sa C: Neuronal plasticity and survival in mood disorders. Biol Psychiatry 2000,48(8):732–739. 10.1016/S0006-3223(00)00935-5PubMedView ArticleGoogle Scholar
- Klop EM, Mouton LJ, Hulsebosch R, Boers J, Holstege G: In cat four times as many lamina I neurons project to the parabrachial nuclei and twice as many to the periaqueductal gray as to the thalamus. Neuroscience 2005,134(1):189–197. 10.1016/j.neuroscience.2005.03.035PubMedView ArticleGoogle Scholar
- Suzuki R, Morcuende S, Webber M, Hunt SP, Dickenson AH: Superficial NK1-expressing neurons control spinal excitability through activation of descending pathways. Nat Neurosci 2002,5(12):1319–1326. 10.1038/nn966PubMedView ArticleGoogle Scholar
- Woolf CJ, Costigan M: Transcriptional and posttranslational plasticity and the generation of inflammatory pain. Proc Natl Acad Sci U S A 1999,96(14):7723–7730. 10.1073/pnas.96.14.7723PubMed CentralPubMedView ArticleGoogle Scholar
- Song XS, Cao JL, Xu YB, He JH, Zhang LC, Zeng YM: Activation of ERK/CREB pathway in spinal cord contributes to chronic constrictive injury-induced neuropathic pain in rats. Acta Pharmacol Sin 2005,26(7):789–798. 10.1111/j.1745-7254.2005.00123.xPubMedView ArticleGoogle Scholar
- Thiels E, Kanterewicz BI, Norman ED, Trzaskos JM, Klann E: Long-term depression in the adult hippocampus in vivo involves activation of extracellular signal-regulated kinase and phosphorylation of Elk-1. J Neurosci 2002,22(6):2054–2062.PubMedGoogle Scholar
- Mizuno M, Yamada K, Maekawa N, Saito K, Seishima M, Nabeshima T: CREB phosphorylation as a molecular marker of memory processing in the hippocampus for spatial learning. Behav Brain Res 2002,133(2):135–141. 10.1016/S0166-4328(01)00470-3PubMedView ArticleGoogle Scholar
- Einat H, Yuan P, Gould TD, Li J, Du J, Zhang L, Manji HK, Chen G: The role of the extracellular signal-regulated kinase signaling pathway in mood modulation. J Neurosci 2003,23(19):7311–7316.PubMedGoogle Scholar
- Davis S, Vanhoutte P, Pages C, Caboche J, Laroche S: The MAPK/ERK cascade targets both Elk-1 and cAMP response element-binding protein to control long-term potentiation-dependent gene expression in the dentate gyrus in vivo. J Neurosci 2000,20(12):4563–4572.PubMedGoogle Scholar
- Itoh T, Abe K, Tokumura M, Horiuchi M, Inoue O, Ibii N: Different regulation of adenylyl cyclase and rolipram-sensitive phosphodiesterase activity on the frontal cortex and hippocampus in learned helplessness rats. Brain Res 2003,991(1–2):142–149. 10.1016/j.brainres.2003.08.007PubMedView ArticleGoogle Scholar
- Carlezon WA Jr., Duman RS, Nestler EJ: The many faces of CREB. Trends Neurosci 2005.Google Scholar
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